Glad I might be able to help you.
It is not my idea but is one hell of a buff stopper.
I have some info here,
It is described as a 375/338 or 375 Taylor
Same idea as the 416 Chatfield taylor but using a 375 projectile instead
Geoff McDonald at WOODLEIGH BULLETS recomends a muzzle velocity between 1900 and 2400 for the round nose 300gn projectiles which give brilliant penetration.
His 235 gn projectiles have a recomended speed of between 1900 and 2800 fps
Always remember ,its not the speed of a bullet that kills but the penetration..

Go to google and type in 375/338 or 375 taylor and it should give you a heap of info..
Al